JP2005189038A - Trip control system for recirculation pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recirculation pump trip control system for optimizing the number of tripped recirculation pumps, according to the amount of fuel loaded into a nuclear reactor, in order to further enhance the stability of the nuclear reactor, when a main steam pipe is closed as to an improved boiling water reactor. <P>SOLUTION: This recirculation pump trip control system is installed in a boiling water nuclear power plant, having a plurality of internal recirculation pumps in a nuclear reactor, wherein the recirculation pumps are partly caused to trip when the main steam pipe is closed. The number of recirculation pumps tripped can be selectively set between four and eight, for example, with a fuel rod body number signal 401, etc. on the number of fuel rod bodies being loaded into the nuclear reactor used as installed unit number setting conditions. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention has a plurality of internal recirculation pumps in the nuclear reactor, and when the main steam pipe for sending steam from the nuclear reactor to the turbine is closed, a part of the recirculation pump is tripped. The present invention relates to a recirculation pump trip control system in a boiling water nuclear power plant.

  There are two types of boiling water reactors (BWR): a recirculation pump is provided outside the reactor pressure vessel, and a recirculation pump is provided inside (internal pump method). An internal-pump boiling water reactor is called an improved boiling water reactor (ABWR), and usually has 10 internal recirculation pumps (internal pumps), for example. When the main steam pipe for sending steam from the reactor to the turbine is closed, a part of the recirculation pump is tripped (emergency stop), and for this purpose, a recirculation pump trip control system is provided. Examples of internal pump trips disclosed in, for example, Patent Document 1 and Patent Document 2 are known.

  FIG. 8 shows the overall configuration of a conventional recirculation pump trip control system in ABWR. The reactor 1 is connected to a main steam pipe (MS pipe) 3 (3a) for sending steam generated by combustion of fuel rods in the core 2 to a turbine not shown. This main steam pipe 3 is usually provided in four systems, and each main steam pipe 3 is provided with a main steam stop valve (MSV) 4 (4a) and a main steam control valve (CV) 5 (5a). It has been. In the figure, only the main steam pipes 3a of the four main steam pipes 3a to 3d are shown, and the others are not shown.

  The main steam stop valve 4 and the main steam control valve 5 are closed to protect the turbine when the load of the generator is cut off or when the turbine trips (the main steam control valve 5 is closed rapidly). As a result, the main steam pipe 3 is closed. When the main steam pipe 3 is closed, the pressure of the nuclear reactor 1 is increased and the voids are reduced, and the reactivity is input to the core 2 due to the reduction of the voids, thereby increasing the output. In order to suppress the increase in output due to the input of reactivity, ABWR has a plurality of recirculation pumps (internal pumps) 6 (6a to 6a) installed in the lower part of the pressure vessel of the reactor 1 (10 in the illustrated example). 6j) is tripped to prevent void reduction in the core. With regard to this recirculation pump trip (RPT), in the conventional recirculation pump trip control system, for example, the optimum number of trips determined in advance, such as tripping the four recirculation pumps 6a and 6b and 6f and 6g, is determined. Fixedly set.

  Here, the recirculation pumps 6a to 6j are divided into independent recirculation pump power supply systems such as 6a and 6b, 6c to 6e, 6f and 6g, and 6h to 6j. The power supply system of the recirculation pumps 6a and 6b and the power supply system of the recirculation pumps 6f and 6g include a bus 7 (7a, 7c), a circuit breaker 8 (8a, 8c) that is opened and closed by an external operation, and a transformer 9 ( 9a, 9c), a disconnector 10 (10a, 10b, 10f, 10g) that functions to protect the device, and an ASD 11 (11a, 11b, 11f, 11g) that bears an inverter function. The power supply system of the recirculation pumps 6c to 6e and the power supply system of the recirculation pumps 6h to 6j include a bus 7 (7b, 7d), a circuit breaker 8 (8b, 8d), a transformer 9 (9b, 9d), and a disconnection. In addition to the apparatus 10 (10c-10e, 10h-10j) and ASD11 (11c-11e, 11h-11j), the MG set 12 (12a, 12b) is provided. This MG set 12 is formed by combining a generator with an electric motor having a flywheel.

  The trips of the recirculation pumps 6a, 6b, 6f, 6g are performed as follows under the control of the RPT facility (recirculation pump trip facility) 100. In the RPT equipment 100, a valve closing condition determination circuit 101 for determining a condition for closing the main steam stop valve 4 and the main steam control valve 5 corresponds to four main steam pipes 3a to 3d, 4 of 101a to 101d. It is provided in the system. As shown in the drawing of the valve closing condition determining circuit 101a, the valve closing condition determining circuit 101a to 101d is a signal for transmitting the closing of the main steam stop valve 4 (4a) or the rapid closing of the main steam control valve 5 (5a). These signals are judged by an OR circuit 104 (only 104a is shown in the figure). That is, when either one of the signals is input, the valve closing condition satisfaction signal 105 (105a to 105d) is output from the OR circuit 104. It should be noted that when the main steam stop valve 4 is closed or the main steam control valve 5 is suddenly closed, as a multiplexing for improving safety, a plurality of signals can be independently generated for reporting each of the close and the quick close. In the following description, it is assumed that four signals are generated for each of the closing signal and the sudden closing signal.

  A valve closing condition establishment signal 105 from the OR circuit 104 is input to an RPT logic 200 which is a means for forming a recirculation pump trip logic (RPT logic). FIG. 9 shows a configuration example of the RPT logic 200. The RPT logic 200 is provided with RPT logic circuits 201 (201a to 201f), to which valve closing condition establishment signals 105a to 105d are input, respectively. The RPT logic circuit 201 (201a to 201f) establishes a 2out of4 condition (2/4 condition) for each of the valve closing condition satisfaction signals 105a to 105d, that is, at least one of the four signals in each of the valve closing condition satisfaction signals 105a to 105d. It is determined whether or not two are transmitted, and if the 2out of4 condition is satisfied, the control signal 103 (103a to 103f) is output.

  9 and 8, the control signal 103a is a signal for opening the circuit breaker 8a, the control signal 103b is a signal for stopping the ASD 11a, the control signal 103c is a signal for stopping the ASD 11b, and the control signal 103d is The signal for opening the circuit breaker 8c, the control signal 103e is a signal for stopping the ASD 11f, and the control signal 103f is a signal for stopping the ASD 11g. Although the recirculation pump 6 can be tripped only by opening the circuit breaker 8, the ASD 11 corresponding to the recirculation pump 6 to be further tripped is stopped in order to increase reliability by multiplexing. is there.

Japanese Patent Laid-Open No. 9-257980 Japanese Patent Laid-Open No. 10-239488

  The greater the number of trips in the recirculation pump trip, the greater the mitigation effect when the output increases. On the other hand, if the number of trips is too large, the effect of a rapid decrease in the coolant flow rate in the core becomes too great, and the minimum limit output ratio indicating the thermal integrity of the fuel becomes severe. For this reason, there is an optimum number of recirculation pump trips. The optimum number depends on the void reactivity coefficient (void coefficient). In other words, the reactivity input accompanying the increase in pressure when the main steam pipe is closed increases as the void reactivity coefficient increases, and the optimal number of trips in the recirculation pump trip to suppress the output increase due to the reactivity input is the void reactivity coefficient. Will depend.

  The void reactivity coefficient correlates with the type and number of fuel rods loaded in the reactor. Previously, there was no significant change in the type of fuel rods or the number of loaded bodies, and therefore the void reactivity coefficient did not change so much. For this reason, conventionally, the optimum number of recirculation pump trips is obtained in advance, and the optimum number of trips is fixedly set to, for example, four as in the above example to constitute a recirculation pump trip control system. It was.

  In recent years, however, nuclear fuel technology has also undergone significant changes, and the types of fuel rods and number of loaded bodies often change greatly. In this situation, if the number of recirculation pump trips remains fixed, the optimization of the number of trips cannot be realized and the minimum limit output ratio becomes strict when the void reactivity factor varies greatly depending on the fuel loaded. It is predicted that this could lead to a situation that would

  The present invention has been made on the basis of the knowledge about the situation in the above boiling water reactor, particularly the improved boiling water reactor, and further improves the stability of the reactor when the main steam pipe is closed. In order to increase this, the purpose is to provide a recirculation pump trip control system that can change the number of trips according to the fuel loaded into the reactor.

  For the above purpose, the present invention has a plurality of internal recirculation pumps in a nuclear reactor, and the main recirculation pumps of the plurality of recirculation pumps are closed when a main steam pipe for sending steam from the nuclear reactor to the turbine is closed. In a recirculation pump trip control system installed in a boiling water nuclear power plant designed to trip a part for trip control of the recirculation pump, the amount of fuel loaded in the nuclear reactor or The number of trips of the recirculation pump can be selectively set using an appropriate parameter correlated with the fuel amount as a set number condition.

  Further, in the present invention, the recirculation pump trip control system as described above can be notified when the set number of recirculation pump trips does not correspond to the set number condition.

  In the present invention, the number of trips can be selectively set by setting the number of fuels loaded into the reactor as the set number condition. For this reason, according to the present invention, it becomes possible to trip the recirculation pump in a more appropriate number according to the operating state of the reactor, and to further increase the stability of the reactor when the main steam pipe is closed. Will be able to.

  Hereinafter, modes for carrying out the present invention will be described. In the first preferred embodiment for carrying out the present invention, on the premise of the current power supply equipment for the recirculation pump, the number of trips of the recirculation pump is set to 4 and 5 according to the fuel condition in the nuclear reactor. The recirculation pump trip control system is configured to switch between these options. FIG. 1 shows the overall configuration of a recirculation pump trip control system according to the first embodiment. This recirculation pump trip control system is different from the conventional recirculation pump trip control system in FIG. 8 in that a circuit breaker 13 (13a to 13j) is newly added between the transformer 9 and the ASD 11. 8 and 9 is different from the conventional recirculation pump trip control system in that an RPT facility 1100 is used instead of the RPT facility 100 in FIG. Other configurations are the same as those of the conventional recirculation pump trip control system shown in FIGS. Therefore, the same code | symbol is attached | subjected to a common part and description about them is abbreviate | omitted suitably by using the above-mentioned description. Note that, in the following, elements that are numbered with a combination of numerals and alphabets have the same number part, and elements that share the same behavior and behavior are described using the numerals of the number part as appropriate. .

  The RPT equipment 1100 has RPT logic 1200 whose specific configuration is shown in FIG. As seen in FIG. 2, the RPT logic 1200 is connected to the trip number changeover switch 300 (300 a to 300 d). The trip number changeover switch 300 is configured so that the number of trips of the recirculation pump can be switched between four and five, and the four-unit selection signal 301 (301a to 301d) or the five-unit selection signal 307 (307a to 307a to 307a). 307d) is input to the RPT logic 1200. Whether to select 4 or 5 units depends on the set number of conditions such as the amount of fuel loaded into the reactor 1 (the number of fuel rods), the degree of burnout in the reactor 1, or the reactivity in the reactor 1. It is decided according to. The extracted burn-up and reactivity can be said to be parameters that correlate with the type and amount of loaded fuel, particularly the number of fuel rods. Therefore, the number of trips is usually selected based on the number of fuel rods as a set number condition.

  Here, in this embodiment, four trip number changeover switches 300 are provided as 300a to 300d. This corresponds to the four valve closing condition establishment signals 105a to 105d from the main steam pipe 3 provided in four systems. Such a configuration is not always necessary, and only one trip number changeover switch 300 can be used.

  The fuel loaded into the nuclear reactor 1 is, for example, MOX fuel. It is assumed that the maximum number of MOX fuel loaded bodies is 360, for example. When the number of fuel rods is as small as 200 or less under these conditions, four units are sufficient from the viewpoint of alleviating pressurized transient events, and this is set. When four units are selected by the trip number changeover switch 300, the four unit selection signal 301 is input to the trip number selection circuit 309 (309a and 309b), and the first AND circuit 302 (302a to 302d) in the trip number selection circuit 309 is selected. As a result, the 4-unit setting signal 303 (303a to 303d) is output. When the four-unit setting signal 303 is output, the open / close-type trip switching circuit 304 (304a to 304d) is opened. The trip switching circuit 304 is provided in the signal path where the valve closing condition establishment signal 105 is input to the RPT logic circuit 201g for trip of the recirculation pump 6j that is caused to trip only when the number of trips is five. ing. Although omitted in FIG. 2, a similar trip switching circuit 304 is also provided for the RPT logic circuit 201h for multiplexing trip of the recirculation pump 6j. Therefore, when four units are selected by the trip number changeover switch 300, the valve closing condition satisfaction signal 105 is not input to the RPT logic circuit 201g or the RPT logic circuit 201h. As a result, when the valve closing condition is satisfied, the control signal 103a for opening the circuit breaker 8a and tripping the recirculation pump 6a and the ASD11a are stopped, and the control signal 103b and ASD11b for tripping the recirculation pumps 6a and 6b are detected. Control signal 103c for tripping the recirculation pump 6b by stopping the control, control signal 103d for tripping the recirculation pumps 6f and 6g by opening the circuit breaker 8c, and control signal 103e for tripping the recirculation pump 6f by stopping the ASD 11f Only the control signal 103f for stopping the ASD 11g and tripping the recirculation pump 6g is output, and the control signal 106a for opening the circuit breaker 13j and tripping the recirculation pump 6j and the ASD 11j are stopped to turn off the recirculation pump 6j. The control signal 106b for tripping is not output It becomes door. That is, only the four recirculation pumps 6a, 6b, 6f, and 6g are tripped.

  On the other hand, when the number of fuel rods loaded in the nuclear reactor 1 is 200 or more, it is necessary to set the number to 5 from the viewpoint of mitigating pressurized transient events. When five units are selected by the trip number changeover switch 300, five unit selection signals 307 (307a to 307d) are input to the trip number selection circuit 309, and the second AND circuit 308 (308a to 308d) in the trip number selection circuit 309 is input. As a result, the 5-unit setting signal 305 (305a to 305d) is output. When the five-unit setting signal 305 is output, the trip switching circuit 304 is closed. Therefore, when five units are selected by the trip number changeover switch 300, the valve closing condition satisfaction signal 105 is also input to the RPT logic circuit 201g and the RPT logic circuit 201h. As a result, the control signal 106a and the control signal 106b are also output, the circuit breaker 13j is opened, the ASD 11j is stopped, and the recirculation pump 6j is tripped. That is, the five recirculation pumps 6a, 6b, 6f, 6g, and 6j are tripped.

  In this embodiment, the recirculation pumps 6a, 6b, 6f, 6g, and 6j are trip targets. However, the circuit breaker 13 is added between the transformer 9 and the ASD 11 as in this embodiment. If so, any of the recirculation pumps 6a to 6j can be individually set as a trip target. Therefore, the recirculation pump to be tripped can be arbitrarily determined. In the present embodiment, the trip switching circuit 304 is provided in the middle of the signal path for inputting the valve closing condition establishment signal 105 to the RPT logic circuits 201j and 201h. Instead, the RPT logic circuits 201j and 201h are provided. You may make it provide in the middle of the signal path of the output signal from.

  As described above, the trip number changeover switch 300 is provided in the RPT logic 1200, and the number of trips can be selectively set based on the number of fuel rods loaded into the reactor 1 as a set number condition. The recirculation pump can be tripped more appropriately for the number of loaded fuel rods, and the stability of the reactor when the main steam pipe is closed can be further improved. Become.

  In the control for selectively setting the number of trips according to the number of loaded fuel rods as described above, the possibility of causing a flaw between the selected number of trips and the actual number of loaded fuel rods cannot necessarily be excluded. In the present invention, in order to cope with this, an RPT setting abnormality monitoring device is provided as means for monitoring the relationship between the set number of trips and the actual number of loaded fuel rods (set number condition). Hereinafter, the RPT setting abnormality monitoring apparatus will be described.

  FIG. 3 shows a configuration example of the RPT setting abnormality monitoring apparatus. The RPT setting abnormality monitoring device 400 of this example is provided with an alarm device 411 which is a means for notifying that the number of trips does not correspond to the set number condition, and a four-unit setting lamp which is a setting number notifying means for the number of trips. 412 and 5 setting lamps 413 are provided. The control circuit for controlling the operation of the notification system includes a monitoring trip number setting signal 312 for the number of trips selected by the trip number changeover switch 300 and fuel rods for the number of fuel rods loaded in the reactor 1. A body number signal 401 is used as an input signal.

  In this embodiment, the monitoring trip number setting signal 312 is established when four trip number changeover switches 300 are selected. Accordingly, the monitoring trip number setting signal 312 directly turns on the four-unit setting lamp 413 and displays that “four-unit RPT setting” because it is established. On the other hand, when the monitoring trip number setting signal 312 is not established, the five-unit setting lamp 412 is turned on via the NOT circuit 403 to display “5-unit RPT setting”.

  The fuel rod number signal 401 is input to the determination circuit 414, where it is compared with the reference fuel rod number signal 416 given by the number change setting means 415. That is, in the number change setting means 415, for example, as shown in the above example, when 200 is used as a guideline for switching between 4 and 5 for the maximum number of loaded fuel rods of 360, these 200 are used as reference fuel rods. The fuel rod number signal 401 is compared with the reference fuel rod number signal 416. When the number of loaded fuel rods is larger than the reference number of fuel rods, a fuel rod number reference or more signal 417 is output. If the monitoring trip number setting signal 312 is established while the fuel rod number reference or more signal 417 is established, that is, the number of loaded fuel rods should be set to five, but the trip number changeover switch 300 sets four. Is selected, the AND circuit 409 is established. As a result, the alarm 411 is turned on, and the “RPT setting abnormality” is reported as the number of set trips is insufficient with respect to the number of loaded fuel rods. On the other hand, when the number of fuel rods reference signal 417 is not established and the monitoring trip number setting signal 312 is also not established, that is, the number of loaded fuel rods should be set to four, but the number of trip number changeover switch 300 sets five. Is selected, the AND circuit 408 is formed by the NOT circuit 402 and the NOT circuit 403. As a result, the alarm 411 is turned on, and the “RPT setting abnormality” can be reported on the assumption that the set trip number is excessive with respect to the number of loaded fuel rod bodies.

  Here, the monitoring trip number setting signal 312 may be obtained directly from the four-unit selection signal 301, the five-unit selection signal 307, the four-unit setting signal 303, or the five-unit setting signal 305. Then, as shown in FIG. 2, the monitoring trip number setting signal 312 is obtained by further ANDing the signals obtained by ANDing the four unit setting signals 303a to 303d and the five unit setting signals 305a to 305d through the NOT circuit. Like to get. On the other hand, the fuel rod number signal 401 is obtained by a signal generating means (not shown) that generates a signal according to the number of fuel rods loaded in the nuclear reactor 1.

  FIG. 4 shows the overall configuration of the recirculation pump trip control system according to the second embodiment. In the present embodiment, the optimum number of trips can be automatically set, for example, between 4 and 8 according to the number of fuel rods loaded in the nuclear reactor 1. To that end, a major change is made to the current power supply equipment for recirculation pumps so that all recirculation pumps can be equally targeted for trips. More specifically, the power supply equipment for the recirculation pump is configured such that the MG set 12 in FIG. 8 is omitted, and the bus 7 (7a-7d) and the transformer 9 (9a-9j) for each of the recirculation pumps 6a-6j. ) Is provided with the breaker 8 (8a to 8j).

  The recirculation pump trip control system of this embodiment includes an RPT facility 2100, and the RPT logic 2200 is provided with an RPT switching logic (RPT number switching logic) 2300 shown in FIG. This RPT switching logic 2300 is a means for selecting the number of trips according to the number of fuel rods by determining the recirculation pump 6 to be tripped according to the number of fuel rods loaded in the reactor 1. These are provided for each recirculation pump corresponding to each of the recirculation pumps 6a to 6j. However, since the configuration of each RPT switching logic 2300 is the same for any recirculation pump 6, only one of them is shown in FIG.

  The RPT switching logic 2300 uses the fuel rod number signal 401 and the RPT establishment signal 501 as input signals. The fuel rod number signal 401 is the same as that in the RPT setting abnormality monitoring device 400 described above. The RPT establishment signal 501 is a signal representing the necessity of the recirculation pump trip, and the 2out of4 condition (2/4 condition) described with reference to FIG. 9 is established in the RPT logic circuit 201 (FIG. 9). Is obtained as an output signal.

  The RPT establishment signal 501 is directly input to the AND circuit 502. On the other hand, the fuel rod number signal 401 enters a conversion circuit 503 where it is converted into a recirculation pump trip number signal 504. That is, the conversion circuit 503 has a fuel rod number / RPT number conversion table in which the correspondence between the number of fuel rods and the number of recirculation pump trips as illustrated in FIG. 5 is determined according to the type of fuel rods. The fuel rod number signal 401 is converted into the RPT number signal 504 based on this conversion table.

  The RPT number signal 504 is input to the adder 505. The adder 505 also receives a set value signal 506 corresponding to the set value of each of the recirculation pumps 6a to 6j. The set value signal 506 is given by the set value input means 507. That is, in the set value input means 507, a set value predetermined for each of the recirculation pumps 6a to 6j is set as in the set value table illustrated in FIG. 5, and a set value signal corresponding to this set value is set. 506 outputs from the set value input means 507. Then, the set value signal 506 is subtracted from the RPT number signal 504 in the adder 505, and the result is determined by the determination circuit 508. When the result is 0 or more, a trip target that specifies that the recirculation pump is a trip target A signal 509 is output from the determination circuit 508.

Here, when the number of fuel rod bodies / RPT number conversion table shown in FIG. 5 is changed to 4 units for 200 units or less and 8 units for 872 units or more, and the range between 5 units to 7 units is illustrated in FIG. In the set value table, since the set values for the recirculation pumps 6c to 6f are 1 to 4, the number of fuel rods is 0 or more in any case, and the set for the recirculation pump 6g. Since the value is 5, the number of fuel rods is 200 or more and becomes 0 or more. For the recirculation pump 6h, the set value is 6, and therefore the number of fuel rods is 331 or more and becomes 0 or more. For the pump 6j, since the set value is 7, the number of fuel rod bodies is 601 or more and becomes 0 or more. For the recirculation pumps 6a and 6b, the set values are 10 and 9, so the number of fuel rod bodies Is less than or equal to 0.
That is, in the present embodiment, the set value table is used to increase the number of fuel rod bodies of the eight recirculation pumps 6c to 6j, excluding the recirculation pumps 6a and 6b, out of the ten recirculation pumps 6a to 6j. In response, trips are made sequentially.

  The trip target signal 509 is input to the AND circuit 502 together with the RPT establishment signal 501. When trip target signal 509 and RPT establishment signal 501 are both established and AND circuit 502 is established, trip instruction signal 510 is output from AND circuit 502. Trip instruction signal 510 is branched into two. For example, when the RPT switching logic 2300 is for the recirculation pump 6c, one of the branch signals from the trip instruction signal 510 opens the circuit breaker 8c and turns on the recirculation pump 6c as shown in the example of FIG. The control signal 103a is tripped, and the other branch signal is the control signal 103b that stops the ASD 11c and trips the recirculation pump 6c. As a result, the recirculation pump 6c is tripped in a multiplexed state by opening the circuit breaker 8c and stopping the ASD 11c.

  The trip target signal 509 and the RPT establishment signal 501 are input to the OR circuit 513 via the NOT circuit 511 to the NOT circuit 512. The OR circuit 513 outputs a non-trip signal 514 when neither the trip target signal 509 nor the RPT establishment signal 501 is established, or when either is established, and the recirculation pump is not subject to non-trip. A lamp 516 indicating that there is a light is turned on.

  As described above, the RPT switching logic 2300 is provided for each recirculation pump, and the necessary recirculation pump is automatically tripped in accordance with the number of fuel rod bodies. In other words, the number of fuel rod bodies individually for each recirculation pump. The number of recirculation pump trips will be further optimized for the operating state of the reactor, and the stability of the reactor will be further improved when the main steam pipe is closed. Will be able to. FIG. 6 shows an example of the effect compared with the case where the number of trips is fixed. The vertical axis in FIG. 6 is the thermal integrity of the fuel, and the horizontal axis is the number of fuel rods. The figure is an example of data for the case where the number of fuel rods is between 331 and 872, and when the number of loaded fuel rods changes during this period, according to the present invention, the target of the thermal integrity of the fuel rods While the range (the range below the target value) can always be achieved, the target range cannot be maintained depending on the number of fuel rods when the number of trips is fixed at either 6 or 7 Will be invited.

  In other words, in the conventional system in which the number of trips is fixed regardless of the number of fuel rods, as shown by the dotted line in the figure, when six units are fixed, an indicator of thermal health if the number of fuel rods is small. However, if the number of fuel rods increases, the recirculation pump trip effect is insufficient and the target range cannot be satisfied. On the other hand, when the number of fuel rods is large, the target range can be satisfied when the number of fuel rods is large. However, when the number of fuel rods is small, the recirculation pump trip effect becomes excessive and the target range is satisfied. Can not do. On the other hand, in the present invention in which the number of trips is adjusted in accordance with the number of fuel rod bodies, the target range can always be achieved regardless of the number of fuel rod bodies, as indicated by the solid line in the figure.

  Even when the number of trips is automatically set according to the number of fuel rods as in this embodiment, it is preferable to provide an RPT setting abnormality monitoring device. A configuration example of the RPT setting abnormality monitoring apparatus is shown in FIG. The RPT setting abnormality monitoring device 600 is provided for each of the recirculation pumps 6a to 6j, similarly to the RPT switching logic 2300, and the designation of the recirculation pump designated as the trip target by the RPT switching logic 2300 is incorrect. When there is an alarm, an alarm device 601 is provided as means for informing that. The control circuit that controls the operation of the alarm device 601 uses the fuel rod number signal 401 and the trip target signal 509 in the RPT switching logic 2300 as input signals.

  The fuel rod number signal 401 is input to the determination circuit 602. In the determination circuit 602, data on the relationship between the number of fuel rods obtained from the correspondence data 603 formed as the fuel rod body / trip target pump correspondence table as exemplified in the figure and the target of trip of the recirculation pump. If the recirculation pump is not to be a trip target, a non-trip target signal 604 is output. This non-trip target signal 604 is input to the AND circuit 605 together with the trip target signal 509. When both the non-trip target signal 604 and the trip target signal 509 are established, the AND circuit 605 is established, the alarm 601 is lit, and the recirculation pump trip designation is incorrect for the number of loaded fuel rod bodies. “RPT setting error” can be reported as being. In the embodiment described above, a method for reporting an error in specifying a trip target is used. Alternatively, a method for reporting an error in specifying a trip target exclusion may be used.

  The present invention can be applied to trip control of a recirculation pump in an improved boiling water reactor of an internal recirculation pump system. And by applying the present invention, it is possible to further increase the stability of the reactor when the main steam pipe is closed by tripping the recirculation pump with a more appropriate number according to the operating state of the reactor It becomes. Therefore, the present invention greatly contributes to further improving the safety of the improved boiling water reactor.

It is a figure which shows the whole structure of the recirculation pump trip control system by 1st Embodiment. It is a figure which shows the structure of the RPT logic in the RPT installation of FIG. It is a figure which shows the structure of the RPT setting abnormality monitoring apparatus in 1st Embodiment. It is a figure which shows the whole structure of the recirculation pump trip control system by 2nd Embodiment. It is a figure which shows the specific structure of the RPT switching logic integrated in RPT logic in the RPT installation of FIG. It is a figure which shows the example compared with the case where the number of trips is fixed about the effect by this invention. It is a figure which shows the structure of the RPT setting abnormality monitoring apparatus in 2nd Embodiment. It is a figure which shows the whole structure of the conventional recirculation pump trip control system. It is a figure which shows the structure of the RPT logic in the RPT installation of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reactor 3 Main steam pipe 6 Recirculation pump 300 Trip number change switch 400 RPT setting abnormality monitoring device 401 Fuel rod number signal 1100, 2100 Recirculation pump trip equipment 1200, 2200 RPT logic 2300 RPT switching logic

Claims (2)

The reactor has a plurality of internal recirculation pumps, and when the main steam pipe for sending steam from the reactor to the turbine is closed, a part of the plurality of recirculation pumps is tripped. In a recirculation pump trip control system installed in a boiling water nuclear power plant for trip control of the recirculation pump,
The number of trips of the recirculation pump can be selectively set using a quantity of fuel loaded in the nuclear reactor or an appropriate parameter correlated with the quantity of fuel as a set number condition. Circulation pump trip control system. 2. The recirculation pump trip control system according to claim 1, wherein when the set number of recirculation pump trips does not correspond to the set number of conditions, it can be reported.

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